JPH0988664A - Control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of smoke caused by the response delay of an exhaust gas recirculation mechanism and prevent the abrupt change of output torque at the time of the acceleration of a Diesel engine. SOLUTION: A CPU of an electronic control unit(ECU) 71 calculates the basic injection quantity and the maximum value of the injection fuel burned by the intake air (maximum injection quantity) based on the operating state of an engine 2 detected by a revolving speed sensor 35, an accelerator opening sensor 73, and an intake air pressure sensor 74 in the exhaust gas recirculation type Diesel engine 2. The CPU controls a vacuum switching valve 56 to stop the recirculation of exhaust gas at the time of the acceleration of the engine 2, increases the basic injection quantity as time elapses, and sets the increasing rate smaller as the basic injection quantity approaches the maximum injection quantity. The CPU sets the final fuel injection quantity by limiting the basic injection quantity to the maximum injection quantity. The CPU sets the fuel injection quantity for the engine 2 to the final injection quantity by controlling a fuel injection pump 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine control device having an exhaust gas recirculation mechanism.

[0002]

2. Description of the Related Art The conventional fuel injection amount control of a diesel engine is generally as follows. The basic injection amount to the diesel engine is calculated from the accelerator opening, engine speed, etc. Based on the engine speed, intake pressure, intake temperature, etc., the maximum value (maximum injection amount) of the amount of injected fuel that is burned by the intake air to the diesel engine is obtained. The final injection amount is set by limiting the basic injection amount by the maximum injection amount, and the fuel injection pump is controlled so that the actual injection amount matches this final injection amount. In particular, during acceleration of the diesel engine, it is effective to gradually increase (null) the basic injection amount with time to suppress a sudden increase in the basic injection amount and mitigate the acceleration shock.

Further, in the conventional diesel engine, in order to suppress the generation of nitrogen oxides in the exhaust gas, a part of the exhaust gas is taken out from the exhaust passage and recirculated to the intake passage, so-called EGR (exhaust gas). Some have a recirculation mechanism. This EGR mechanism uses a flow control valve (EG) in an exhaust gas recirculation passage that connects an exhaust passage and an intake passage of an internal combustion engine.
R valve) is provided to adjust the EG according to the operating state of the internal combustion engine
The R valve is opened and closed to adjust the recirculation amount of exhaust gas. This EGR is performed when the deviation between the maximum injection amount and the final injection amount to the diesel engine is a predetermined value or more, and is stopped when the deviation becomes smaller than the predetermined value. At the time of acceleration in which the maximum injection amount becomes the final injection amount, the deviation becomes smaller than the predetermined value, and EGR is stopped. As a result, the shortage of the intake air amount due to EGR is eliminated, and the generation of smoke is suppressed.

However, even if a command signal for closing the EGR valve is issued, the recirculation of the exhaust gas is not immediately stopped due to the response delay of the EGR valve or the like. Therefore, it is not possible to suppress the occurrence of smoke as intended. Therefore, it has been proposed to prevent the generation of smoke due to the response delay of the EGR valve by reducing the maximum injection amount by a fixed amount when the EGR is stopped during acceleration (Japanese Patent Laid-Open No. 63-143343). reference).

In a diesel engine equipped with an EGR mechanism, it is possible to use the above two techniques together. That is, as shown in FIG. 8, during acceleration of the diesel engine, the basic injection amount QBA
SE is gradually increased over time. In a period in which the basic injection amount QBASE is smaller than the maximum injection amount QFULL (a period before timing t11), the basic injection amount QBASE becomes the final injection amount QFIN. At timing t11, the maximum injection amount QFULL and the final injection amount QFIN
When the deviation from the above becomes smaller than a predetermined value, the maximum injection amount QFULL is set to a constant amount (transient intake pressure correction coefficient) MQF in order to prevent smoke generation due to the response delay of the EGR valve closing.
Reduce PT only. After that (after timing t12),
The maximum injection amount QFULL is gradually increased with time and is returned to a value according to the engine speed, intake pressure, intake temperature, etc. at that time (timing t13). The maximum injection amount QFULL becomes the final injection amount QFIN after the timing t11.

[0006]

However, in the above-mentioned technique, although the generation of smoke due to the response delay of the EGR valve can be suppressed, the output torque of the diesel engine suddenly changes due to the rapid decrease of the fuel injection amount. However, the passengers are shocked by the change. In addition to this, the reduction of the injection amount is performed when the injection fuel is increased for acceleration. Therefore, even though the driver wants to accelerate, the acceleration is temporarily stopped, so that the driver's needs are not met and drivability is deteriorated.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to suppress a sudden change in output torque while suppressing smoke generation due to a response delay when EGR is stopped during acceleration of a diesel engine. It is to provide a control device for a diesel engine that can be prevented.

[0008]

In order to achieve the above object, the present invention involves, as shown in FIG. 1, a fuel injection pump M2 for supplying fuel to a diesel engine M1 and combustion of the fuel and intake air. Exhaust gas recirculation mechanism M for recirculating a part of exhaust gas to the diesel engine M1
3, an operating state detecting means M4 for detecting an operating state of the diesel engine M1, and a basic injection amount calculating means M5 for calculating a basic injection amount to the diesel engine M1 according to the engine operating state by the operating state detecting means M4. And a maximum injection amount calculation means M6 for calculating the maximum value of the amount of fuel injected into the diesel engine M1 in the intake air based on the engine operation state by the operation state detection means M4, and the diesel engine M1. Acceleration detection means M for detecting the acceleration state
7 and the diesel engine M1 by the acceleration detection means M7
Exhaust gas recirculation control means M8 for stopping the exhaust gas recirculation by the exhaust gas recirculation mechanism M3 at the time of acceleration of
During acceleration of the diesel engine M1 by the acceleration detecting means M7, the basic injection amount by the basic injection amount calculating means M5 is increased with time, and the rate of increase is determined by the basic injection amount by the maximum injection amount calculating means M6. The basic injection amount correction means M9 that decreases as it approaches the maximum injection amount, and the basic injection amount by the basic injection amount correction means M9 are limited by the maximum injection amount by the maximum injection amount calculation means M6 to determine the final fuel injection amount. A final injection amount setting means M10 to be set,
By controlling the fuel injection pump M2, the injection control unit M1 that makes the fuel injection amount to the diesel engine M1 match the final injection amount by the final injection amount setting unit M10.
1 and.

In the present invention, when the operating state detecting means M4 detects the operating state of the diesel engine M1, the basic injection amount calculating means M5 calculates the basic injection amount to the diesel engine M1 according to the engine operating state. In addition, the maximum injection amount calculation means M6 determines whether the diesel engine M
The maximum value of the injected fuel quantity that is burned by the intake air to 1 is calculated.

When the acceleration detection means M7 detects the acceleration state of the diesel engine M1, the exhaust gas recirculation control means M8 stops the exhaust gas recirculation by the exhaust gas recirculation mechanism M3. The basic injection amount correcting means M9 increases the basic injection amount by the basic injection amount calculating means M5 with time, and the rate of increase is such that the basic injection amount approaches the maximum injection amount by the maximum injection amount calculating means M6. Make it smaller. The final injection amount setting means M10 sets the final fuel injection amount by limiting the basic injection amount by the basic injection amount correcting means M9 to the maximum injection amount by the maximum injection amount calculating means M6. The injection control unit M11 controls the fuel injection pump M2 to match the fuel injection amount to the diesel engine M1 with the final injection amount.

Therefore, during acceleration of the diesel engine M1, the exhaust gas recirculation mechanism M3 operates with a delay in response and stops the exhaust gas recirculation. During this acceleration,
Only by increasing the basic injection amount, it is possible to make the injection amount (amount smaller than the maximum injection amount) in consideration of suppression of smoke generation due to the response delay of the exhaust gas recirculation mechanism M3. That is, if the basic injection amount is increased to once match the maximum injection amount and then the same injection amount is attempted to match the injection amount in which the response delay is considered, it is necessary to reduce the injection amount by a large amount at a time. However, in the present invention, such a weight reduction is unnecessary. As described above, when the exhaust gas recirculation mechanism M3 is operated, when the basic injection amount becomes the injection amount in which the response delay of the mechanism M3 is taken into consideration, the generation of smoke is suppressed.

Moreover, the rate of increase of the basic injection amount decreases as the basic injection amount approaches the maximum injection amount. In other words, the basic injection amount gradually increases as it approaches the maximum injection amount. Therefore, even after the basic injection amount becomes the injection amount in which the response delay is considered, the maximum injection amount of the basic injection amount is increased as compared with the case where the basic injection amount is increased by the same value as the increase rate before the same injection amount. The time to reach the quantity is delayed. As described above, during the period from when the increase of the basic injection amount is started until when it reaches the maximum injection amount, the basic injection amount does not significantly change. Since the fluctuation of the output torque of the diesel engine M1 corresponding to the final injection amount (in this case, the corrected basic injection amount) is small, the shock due to the change is small. In addition, since there is no reduction correction of the basic injection amount in the above period, the acceleration is not temporarily stopped during the acceleration of the diesel engine M1.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, a vehicle has a diesel engine (diesel engine) 2 having multiple cylinders (for example, four cylinders), and fuel for supplying fuel to a fuel injection nozzle 4 provided for each cylinder of the engine 2. The injection pump 1 is mounted. A drive shaft 5 is rotatably supported by the fuel injection pump 1, and a drive pulley 3 is attached to the tip of the shaft 5 (left end in the figure). A belt or the like is mounted on the drive pulley 3 and the crankshaft 40 of the diesel engine 2, and the rotation of the crankshaft 40 is transmitted to the drive shaft 5 by the drive pulley 3, the belt, and the like.

In the fuel injection pump 1, a fuel feed pump (developed by 90 degrees in the figure) 6 which is a vane type pump is provided on the drive shaft 5. A disk-shaped pulsar 7 is attached to the base end (right end in the figure) of the drive shaft 5. On the outer peripheral surface of the pulsar 7, the same number as the number of cylinders of the diesel engine 2 (in this case, 4
The number of missing teeth is formed at equal angular intervals, and a predetermined number of protrusions are formed at equal angular intervals between adjacent missing teeth. The base end of the drive shaft 5 is connected to the cam plate 8 via a coupling (not shown).

A roller ring 9 is provided between the pulsar 7 and the cam plate 8, and a plurality of cam rollers 10 facing the cam face 8a of the cam plate 8 are attached along the circumference of the roller ring 9. . Cam face 8a
Are provided as many as the number of cylinders of the diesel engine 2. The cam plate 8 is constantly urged and engaged with the cam roller 10 by the spring 11.

A fuel pressurizing plunger 12 is attached to the cam plate 8, and these 8 and 12 interlock with the rotation of the drive shaft 5 and rotate integrally. That is,
The rotational force of the drive shaft 5 is transmitted to the cam plate 8 via a coupling (not shown). By this transmission, the cam plate 8 is engaged with the cam roller 10 while rotating, and reciprocates in the left-right direction in the figure by the same number as the number of cylinders.
With this reciprocating motion, the plunger 12 rotates and reciprocates in the same direction. That is, the plunger 12 moves forward (lifts) when the cam face 8a of the cam plate 8 rides on the cam roller 10 of the roller ring 9, and conversely moves the plunger 12 back when the cam face 8a rides on the cam roller 10. .

The plunger 12 is fitted in a cylinder 14 formed in the pump housing 13, and a high pressure chamber 15 is formed between the tip end surface of the plunger 12 and the inner bottom surface of the cylinder 14. In the outer periphery of the tip of the plunger 12, there are as many suction grooves 16 as the number of cylinders of the diesel engine 2.
And a distribution port 17 are formed. A distribution passage 18 and a suction port 19 are formed in the pump housing 13 corresponding to the suction groove 16 and the distribution port 17.

The drive shaft 5 rotates and the fuel feed pump 6 is driven, whereby the fuel in the fuel tank (not shown) is supplied to the fuel chamber 21 through the fuel supply port 20. Further, during the suction stroke in which the plunger 12 is moved back and the high pressure chamber 15 is depressurized, the suction groove 1
By communicating one of 6 with the suction port 19, the fuel in the fuel chamber 21 is introduced into the high pressure chamber 15. On the other hand, during the compression stroke in which the plunger 12 is moved forward and the high pressure chamber 15 is pressurized, fuel is pressure-fed from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder and injected.

In the pump housing 13, a spill passage 22 for fuel overflow (spill) is formed which connects the high pressure chamber 15 and the fuel chamber 21. An electromagnetic spill valve 23 for adjusting the spill of fuel from the high pressure chamber 15 is provided in the middle of the spill passage 22. The electromagnetic spill valve 23 is a normally open type valve having a coil 24, and when the coil 24 is in a non-energized (off) state, the valve body 25 is opened and the high pressure chamber 1
The fuel in 5 is spilled into the fuel chamber 21. When the coil 24 is energized (turned on), the valve body 25 is closed, and the spill of fuel from the high-pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, by changing the energization time of the electromagnetic spill valve 23, the valve 23 is controlled to be closed and opened.
The spill of fuel from the high pressure chamber 15 to the fuel chamber 21 is adjusted. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the fuel inside the high pressure chamber 15 is depressurized and the fuel injection from the fuel injection nozzle 4 is stopped. That is, even if the plunger 12 moves forward, the fuel pressure in the high-pressure chamber 15 does not rise and the fuel is not injected from the fuel injection nozzle 4 while the electromagnetic spill valve 23 is open. By controlling the closing / opening timing of the electromagnetic spill valve 23 during the forward movement of the plunger 12, the fuel injection end timing of the fuel from the fuel injection nozzle 4 is changed and the fuel injection amount is adjusted.

Below the pump housing 13, a timer device (developed by 90 degrees in the figure) 26 for changing the fuel injection timing is provided. This timer device 2
6 is a cam face 8a by changing the position of the roller ring 9 with respect to the rotation direction of the drive shaft 5.
Changes the timing of engagement with the cam roller 10, that is, the reciprocating drive timing of the cam plate 8 and the plunger 12.

The timer device 26 is driven by control hydraulic pressure, and includes a timer housing 27 and the housing 2.
7, the timer piston 28 is fitted in the inside of the timer housing 27, and the timer piston 28 is urged by the low pressure chamber 29 on one side (the left side in the drawing) of the timer housing 27 to the pressure chamber 30 on the other side (the right side in the drawing). It is composed of a timer spring 31 and the like.
The timer piston 28 is connected to the roller ring 9 via the slide pin 32.

The fuel pressurized by the fuel feed pump 6 is introduced into the pressure chamber 30. The position of the timer piston 28 is determined by the equilibrium relationship between the fuel pressure and the urging force of the timer spring 31. With this, the position of the roller ring 9 is determined,
The reciprocating timing of the plunger 12 is determined via the cam plate 8.

The timer device 26 is provided with a timing control valve (TCV) 33 in order to adjust the fuel pressure acting as the control oil pressure of the timer device 26. That is, the pressurizing chamber 30 and the low pressure chamber 29 of the timer housing 27 are communicated with each other by the communication passage 34, and the TCV 33 is interposed in the communication passage 34. This T
The CV 33 is a solenoid valve that is opened and closed by a duty-controlled energization signal, and the fuel pressure in the pressurizing chamber 30 is adjusted by adjusting the opening of the TCV 33. And
By the adjustment, the reciprocating movement timing of the plunger 12 is changed, and the fuel injection timing of each fuel injection nozzle 4 is adjusted.

On the upper part of the roller ring 9, a rotation speed sensor 35 forming a part of the operating condition detecting means is provided.
Is attached so as to face the outer peripheral surface of the. The rotation speed sensor 35 is composed of an electromagnetic pickup coil, detects the passage of the protrusions formed on the outer peripheral surface of the pulsar 7 when they cross, and outputs a timing signal (engine rotation pulse) corresponding to the engine rotation speed NE. To do. Since the rotation speed sensor 35 is integrated with the roller ring 9, the timer device 2
Regardless of the control operation of No. 6, a reference timing signal is output to the plunger lift at a constant timing.

Next, the diesel engine 2 will be described. In this engine 2, the cylinder 41 and the piston 42
A main combustion chamber 44 corresponding to each cylinder is formed by the cylinder head 43. Further, a sub combustion chamber 45 communicating with each of the main combustion chambers 44 is provided corresponding to each cylinder. Then, the fuel is injected from each fuel injection nozzle 4 into each auxiliary combustion chamber 45. A well-known glow plug 46 as a start assist device is attached to each sub-combustion chamber 45.

A turbocharger 48 is mounted on the diesel engine 2. The turbocharger 48 includes a turbine 51 arranged in the middle of the exhaust pipe 50 and an intake pipe 4
7 is provided with a compressor 49 and a shaft connecting the turbine 51 and the compressor 49. The exhaust pipe 50 has a turbocharger 48.
A waste gate valve 52 for adjusting the supercharging pressure by

The exhaust pipe 50 and the intake pipe 47 are connected in a communicating state by a return pipe 54 as an exhaust gas recirculation path, and a part of the exhaust gas in the exhaust pipe 50 can be returned to the intake pipe 47. . An EG as a flow control valve for adjusting the recirculation amount (EGR amount) of the exhaust gas is provided in the middle of the recirculation pipe 54.
An R valve 55 is provided. This EGR valve 55
The negative pressure introduced into the diaphragm chamber of is regulated by a vacuum switching valve (VSV) 56. V
The SV 56 is controlled by the on / off duty signal. More specifically, as the duty ratio (final EGR duty ratio DEFIN) increases, the current value to VSV 56 increases, and the negative pressure in the diaphragm chamber of EGR valve 55 increases. Accordingly, the flow passage area of the reflux pipe 54 increases,
The amount of EGR increases. And, these reflux tubes 54, E
The GR valve 55 and the VSV 56 constitute an exhaust gas recirculation mechanism.

Further, in the middle of the intake pipe 47, there is provided a throttle valve 58 which is opened / closed in association with the depression amount of the accelerator pedal 57. A bypass passage 59 is provided in the intake pipe 47 in parallel with the throttle valve 58, and a bypass throttle valve 60 is provided in the middle of the bypass passage 59. The bypass throttle valve 60 is controlled to be opened / closed by an actuator 63 having a two-stage diaphragm chamber driven by two VSVs 61 and 62. This bypass throttle valve 60
Is controlled to open and close according to various operating states. For example, the bypass throttle valve 60 is in a half-open state to reduce noise and vibration during idle operation of the diesel engine 2, is fully open in normal operation, and is fully closed in order to smoothly stop when operation is stopped. It

The electromagnetic spill valve 2 provided on the fuel injection pump 1 and the diesel engine 2 as described above.
3, TCV33, glow plug 46 and each VSV56,
Reference numerals 61 and 62 are respectively connected to an electronic control unit (hereinafter simply referred to as “ECU”) 71, and the drive timings thereof are controlled by the ECU 71.

In order to detect the operating state of the diesel engine 2, the following various sensors are provided in addition to the rotational speed sensor 35 described above. An intake air temperature sensor 72 for detecting the intake air temperature THA is attached near the air cleaner 64 at the inlet of the intake pipe 47.

In the intake pipe 47, an accelerator opening sensor 73 for detecting the accelerator opening ACCP corresponding to the load of the diesel engine 2 from the opening / closing position of the throttle valve 58.
Is provided. The intake pressure VPI after supercharging by the turbocharger 48 is provided near the intake port 53.
An intake pressure sensor 74 that detects M is provided. The accelerator opening sensor 73 and the intake pressure sensor 74 form a part of the operating state detecting means together with the rotational speed sensor 35 described above.

Further, in the diesel engine 2, a water temperature sensor 75 for detecting the cooling water temperature THW and a crank angle for detecting the rotation reference position of the crankshaft 40, for example, the rotation position of the crankshaft 40 with respect to the top dead center of a specific cylinder. A sensor 76 is provided. The transmission (not shown) is provided with a vehicle speed sensor 77 that detects the vehicle speed (vehicle speed) SP by turning on / off the reed switch 77b with a magnet 77a rotated by the rotation of the gear.

Each of the sensors 35, 72 to 77 described above is an EC.
Each is connected to U71. Then, the ECU 71
Is based on the detection signals of the sensors 35, 72 to 77, the electromagnetic spill valve 23, the TCV 33, the glow plug 46 and the VS.
V56, 61, 62 are controlled.

Next, the structure of the above-mentioned ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 includes a central processing unit (CPU) 81, a predetermined control program,
Read-only memory (ROM) that stores maps in advance
82, a random access memory (RAM) 83 for temporarily storing calculation results of the CPU 81, and a backup RAM 84 for storing prestored data. These units are connected to the input port 85 and the output port 86 by a bus 87. There is.

The intake temperature sensor 72, the accelerator opening sensor 73, the intake pressure sensor 74 and the water temperature sensor 75 described above are
Input port 85 via buffers 88, 89, 90, 91, multiplexer 92 and A / D converter 93, respectively.
It is connected to the. The rotation speed sensor 35, the crank angle sensor 76, and the vehicle speed sensor 77 are connected to the input port 85 via the waveform shaping circuit 95. The CPU 81 reads the detection signals of the sensors 35, 72 to 77 via the input port 85.

The electromagnetic spill valve 23, the TCV 33, the glow plug 46, and the VSVs 56, 61, 62 are connected to the output port 86 via drive circuits 96, 97, 98, 99, 100, 101, respectively. The CPU 81, based on the input values read from the sensors 35, 72 to 77, the electromagnetic spill valve 23, the TCV 33, the glow plug 46.
And VSV 56, 61, 62 are preferably controlled.

Next, the operation and effect of this embodiment configured as described above will be described. The flowcharts of FIGS. 4 and 5 show a routine for controlling the fuel injection amount in the fuel injection pump 1 among the processes executed by the CPU 81. The flowchart of FIG. 6 shows a routine for EGR control in the VSV 56. Each of these routines is executed every predetermined time.

In the fuel injection control routine, the CPU 81 determines in step 101 the engine speed NE by the speed sensor 35 and the intake pressure VPI by the intake pressure sensor 74.
M and accelerator opening AC by accelerator opening sensor 73
Read each CP.

Subsequently, in steps 102 to 105, the maximum injection amount QFULL which is the maximum value of the injection fuel amount burned by the intake air to the diesel engine 2 is calculated based on the engine speed NE and the intake pressure VPIM. . First, at step 102, referring to the map stored in the ROM 82, the maximum injection amount correction term QFUL corresponding to the engine speed NE at step 101 is referred to.
B and the offset term QFULO are calculated respectively. At step 103, the intake pressure VPIM at step 101 is referred to by referring to the map stored in the ROM 82.
The basic intake pressure correction coefficient MQFPB corresponding to is calculated.
In step 104, the transient intake pressure correction coefficient M is calculated from the basic intake pressure correction coefficient MQFPB in step 103.
Intake pressure correction coefficient MQFP by subtracting QFPT
Is calculated. The transient intake pressure correction coefficient MQFPT is used to reduce the intake pressure correction coefficient MQFP during a transient, and is a constant value here. Then, in step 105, the maximum injection amount correction term QFULB in step 102 is multiplied by the intake pressure correction coefficient MQFP in step 104, and the offset term QFULO in step 102 is added, and the addition result is obtained. Is the maximum injection amount QFULL.

Then, in step 106, the ROM
Referring to the map stored in 82, the step 10
The governor injection amount QGOV corresponding to the accelerator opening ACCP at 1 and the engine speed NE is calculated. Step 1
At 07, the injection amount QNMS for determining the switching timing of the two acceleration smoothing amounts corresponding to the engine speed NE is calculated with reference to the map stored in the ROM 82. Here, the injection amount QNMS increases as the engine speed NE increases.
The relationship between the two NEs and QNMS is defined in advance so that

Next, the routine proceeds to step 108 in FIG. 5, where the cylinder pre-correction final injection amount QFIN stored in the previous control cycle is stored.
AOL is read, and it is determined whether the governor injection amount QGOV in step 106 is equal to or larger than the final injection amount QFINAOL. That is, it is determined whether or not the injection amount requested by the driver (governor injection amount QGOV) is equal to or larger than the final injection amount QFIN finally supplied to the diesel engine 2 by the fuel injection pump 1 in the previous control cycle. By the determination, it is determined whether or not the diesel engine 2 is in the acceleration state (whether or not the driver desires acceleration).

When the determination condition of step 108 is satisfied (QGOV ≧ QFINAOL), it is determined that the diesel engine 2 is in an accelerating state (the driver wants to accelerate), and the process proceeds to step 109. To do. In step 109, from the maximum injection amount QFULL in step 105, the last pre-cylinder correction final injection amount QFINA is calculated.
The value obtained by subtracting OL (deviation ΔQ) is the value obtained in step 10 above.
It is determined whether the injection amount is larger than the injection amount QNMS at 7.

If the determination condition of step 109 is satisfied (ΔQ> QNMS), the process proceeds to step 110,
An acceleration smoothing injection amount QSMA for suppressing a sudden change in output torque during acceleration is calculated. This acceleration smoothed injection amount QSMA is the last before-cylinder correction final injection amount QFI.
It is obtained by subjecting NAOL to accelerated anneal processing. Specifically, referring to the first map stored in the ROM 82, the first acceleration smoothing amount MQSM corresponding to the accelerator opening ACCP and the engine speed NE at that time is stored.
AD1 is obtained, and this is calculated as the final injection amount QFI before cylinder correction.
Acceleration smoothing injection amount QSM by adding to NAOL
Get A. After calculating the accelerated smoothing injection amount QSMA in this way, the routine proceeds to step 112.

On the other hand, when the determination condition of step 109 is not satisfied (ΔQ ≦ QNMS), step 1
11, and referring to the second map stored in the ROM 82, the second acceleration smoothing amount MQSMA corresponding to the accelerator opening ACCP and the engine speed NE at that time.
Find D2. By adding this value MQSMAD2 to the pre-cylinder uncorrected final injection amount QFINAOL, the acceleration smoothed injection amount QSMA is obtained. After calculating the accelerated smoothing injection amount QSMA in this way, the routine proceeds to step 112.

Particularly, here, the same accelerator opening degree ACC
When compared with P and engine speed NE, the second acceleration smoothing amount MQSMAD2 is the first acceleration smoothing amount MQSM.
The first and second maps are created so as to be smaller than AD1. For this reason, when the second acceleration smoothing amount MQSMAD2 is increased by one, the method of increasing the acceleration smoothing injection amount QSMA depends on the first acceleration smoothing amount MQSM.
This is slower than the case where the dose is increased by AD1. In other words, even if the acceleration smoothing process is performed uniformly, the tendency of the increase of the acceleration smoothing injection amount QSMA changes depending on whether the deviation ΔQ is larger than the injection amount QNMS. When the deviation ΔQ becomes smaller than the injection amount QNMS, the acceleration smoothed injection amount QSMA increases slowly (the increase rate becomes smaller) than before, and eventually the basic injection amount QBASE, which will be described later, reaches the maximum injection amount QFULL. Is given.

At step 112, the step 106 is performed.
Of the governor injection amount QGOV in step 110 or 111 or the acceleration smoothing injection amount QSMA in step 110 or 111, whichever is smaller, and this is selected as the basic injection amount QBA.
Remember as SE. Then, the process proceeds to step 115.

On the other hand, when the above-mentioned determination condition of step 108 is not satisfied (QGOV <QFINAOL), it is determined that the diesel engine 2 is in the decelerating state (the driver wants to decelerate), and step 113 Move to. In step 113, the deceleration smoothing injection amount QSMD for suppressing the fluctuation of the output torque during deceleration is calculated. This deceleration smoothed injection amount QSMD is obtained by performing deceleration smoothing processing on the cylinder pre-correction final injection amount QFINAOL in the previous control cycle. Specifically, R
With reference to the map stored in the OM 82, the deceleration smoothing amount corresponding to the accelerator opening ACCP and the engine speed NE at that time is calculated, and the deceleration smoothing amount is subtracted from the pre-cylinder pre-correction final injection amount QFINAOL to reduce the deceleration. Further, the injection amount QSMD is obtained.

Then, at step 114, the larger of the governor injection amount QGOV at step 106 and the decelerated smoothing injection amount QSMD at step 113 is performed, as in step 112. It is selected and set as the basic injection amount QBASE. Here, when the diesel engine 2 is in the deceleration state, the deceleration smoothing injection amount QSMD is usually larger than the governor injection amount QGOV, and the deceleration smoothing injection amount QS is the same.
MD is stored as the basic injection amount QBASE. Then, after setting the basic injection amount QBASE, the routine proceeds to step 115.

In step 115, the maximum injection amount QFULL in step 105 and step 1
The smaller one of the basic injection amounts QBASE in 12 or 114 is selected, and this is set as the current pre-correction final injection amount QFINA. Then Step 116
In, the final injection amount QFIN is calculated by adding various corrections to the pre-cylinder final injection amount QFINA according to a previously prepared arithmetic expression.

In step 117, the injection amount command value Vs corresponding to the final injection amount QFIN is output. That is, the fuel is supplied from the fuel injection pump 1 to the fuel injection nozzle 4 by drivingly controlling the electromagnetic spill valve 23 based on the injection amount command value Vs. In step 118, the final injection amount QFIN of this time is set as the last pre-cylinder correction final injection amount QFINAOL in preparation for the next calculation, and this is stored.

In the above fuel injection control routine, C
The processing of steps 102 to 105 by the PU 81 corresponds to the maximum injection amount calculation means, and the processing of step 108 corresponds to the acceleration detection means. The processes of steps 109 to 112 correspond to the basic injection amount calculating device and the basic injection amount correcting device, the processes of steps 115 and 116 correspond to the final injection amount setting device, and the process of step 117 corresponds to the injection control device.

Next, the EGR control routine of FIG. 6 will be described. In this routine, the CPU 81 executes step 2
01, engine speed NE, cooling water temperature THW,
The intake pressure VPIM, the maximum injection amount QFULL, the cylinder pre-correction final injection amount QFINA, and the final injection amount QFIN are read.

In step 202, the water temperature correction coefficient METHW corresponding to the cooling water temperature THW is calculated based on the map of the ROM 82, and in step 203 the intake pressure correction coefficient MEPI corresponding to the intake pressure VPIM.
Calculate M. At step 204, based on the map of the ROM 82, the basic EGR duty ratio DEBS corresponding to the engine speed NE and the final injection amount QFIN.
Calculate E.

In step 205, the injection amount QEGR corresponding to the engine speed NE is calculated. This injection amount QEGR is EGR when the operation state of the diesel engine 2 is EGR.
The engine speed N is used when it is determined whether the valve 55 is opened and the EGR is executed.
It is specified for each E. As the injection amount QEGR,
Under the same engine speed NE, an amount slightly smaller than the injection amount QNMS in the fuel injection control routine of FIGS. 4 and 5 described above is set.

At step 206, the maximum injection amount QFUL
The value (deviation ΔQ) obtained by subtracting the final pre-cylinder injection amount QFINA from L is the injection amount QEG in step 205.
It is determined whether it is larger than R. Here, in general, when the basic injection amount QBASE is larger than the maximum injection amount QFULL, the maximum injection amount QFULL is adopted as the final injection amount before cylinder correction QFINA, so both QFULL,
The deviation ΔQ of QFINA becomes smaller. If the determination condition of step 206 is satisfied (QFULL-QFINA>
QEGR), the process proceeds to step 207, and step 2
To the basic EGR duty ratio DEBSE obtained in step 04, the water temperature correction coefficient METHW obtained in steps 202 and 203
And the intake pressure correction coefficient MEPIM to obtain the final EG
The R duty ratio DEFIN is calculated.

On the other hand, if the determination condition of step 206 is not satisfied (QFULL-QFINA≤QEG
R), the process proceeds to step 208, and the final EGR duty DEFIN is set to "0".

After the execution of step 207 or 208,
In step 209, the final EGR duty ratio DE
The EGR drive signal (of the frequency) corresponding to FIN is VSV5
6 to adjust the EGR valve 55 to an opening degree determined by the final EGR duty ratio DEFIN. After executing step 209, this routine ends.

In the above EGR control routine, the CPU
The processing of steps 206 and 208 by 81 corresponds to the exhaust gas recirculation control means. Therefore, according to both control routines described above, in the period before the timing t1 in FIG. 7, the maximum injection amount QFULL and the uncorrected final injection amount QF before cylinder correction are performed.
The deviation ΔQ from INA (basic injection amount QBASE) is larger than the injection amount QNMS. By the processing of step 110 for each revolution of the fuel injection control routine, the acceleration smoothing injection amount QSMA (basic injection amount QBASE) increases by the first acceleration smoothing amount MQSMAD1 with the passage of time. Also,
In this period, the deviation ΔQ is equal to the injection amount QEGR (<QNM
More than S). Step 20 of EGR control routine
By the processing of 7,209, the final EGR duty ratio DE
FIN is calculated, the opening of the EGR valve 55 is controlled, and the EGR flow rate is adjusted.

At the timing t1, the deviation ΔQ is the injection amount Q.
When it becomes equal to or less than NMS, the processing of step 111 for each revolution of the fuel injection control routine causes the acceleration smoothing injection amount QSMA (basic injection amount QBASE) to be smaller than the first acceleration smoothing amount MQSMAD1 with the passage of time. The acceleration smoothing amount of 2 is increased by MQSMAD2. At this time, the EGR valve 55 is opened and EGR is continued.

At a timing t2 slightly delayed from the timing t1, when the deviation ΔQ becomes equal to or less than the injection amount QEGR,
By the processing of step 208 of the EGR control routine, the final EGR duty ratio DEFIN is changed to "0", and E
The GR valve 55 is closed and the EGR flow rate becomes "0". At this time, the CPU 81 determines that the final EGR duty ratio DE
It takes some time from when the EGR drive signal corresponding to FIN is output to the VSV 56 until the EGR valve 55 closes to stop the EGR. In other words, EG during acceleration
R valve 55 operates with a delay in response, and EG
The exhaust gas recirculation is stopped after a slight delay from the output of the R drive signal.

As described above, in the present embodiment, when the diesel engine 2 is accelerated, the basic injection amount QBASE is only increased, and the injection amount (in consideration of suppressing smoke generation due to the response delay of the EGR valve 55) is taken into consideration. The amount is smaller than the maximum injection amount QFULL). Therefore, if the basic injection amount QBASE is increased to match the maximum injection amount QFULL once as in the prior art and then the injection amount QBASE is tried to match the injection amount in which the response delay is considered, the basic injection amount It is necessary to reduce QBASE by a large amount (transient intake pressure correction coefficient MQFPT) at one time, but in the present embodiment, such a reduction is unnecessary. Then, when the EGR valve 55 operates in this way,
When the basic injection amount QBASE becomes the injection amount in which the response delay of the EGR valve 55 is taken into consideration, the generation of smoke is suppressed.

Moreover, the acceleration smoothing amount related to the increase of the acceleration smoothing injection amount QSMA is from MQSMAD1 to MQSMA.
Since it is switched to D2, the increase rate of the basic injection amount QBASE becomes smaller as the injection amount QBASE approaches the maximum injection amount QFULL. In other words, the basic injection amount QBA
SE gradually increases as it approaches the maximum injection amount QFULL. Even after the basic injection amount QBASE becomes the injection amount in which the response delay is considered, the maximum injection amount of the basic injection amount QBASE is increased as compared with the case where the basic injection amount QBASE is increased by the same value as the increase rate before the same injection amount. QFULL
Arrives late. As described above, in the period from when the increase of the basic injection amount QBASE is started to when the increase of the basic injection amount QBASE is reached to the maximum injection amount QFULL, the basic injection amount QBASE is increased.
There is no big change. Final injection quantity QFIN (in this case,
Since the fluctuation of the output torque of the diesel engine 2 corresponding to the corrected basic injection amount QBASE) is small, the shock due to the change is small. In addition, since there is no reduction correction of the basic injection amount QBASE during the above period, the acceleration is not temporarily stopped during the acceleration of the diesel engine 2.

In addition to the matters described above, the present embodiment has the following effects. (A) First and second acceleration smoothing amounts MQSMAD1, M
The injection amount QNMS for determining the switching timing of QSMAD2 is not set to a constant value, but is changed according to the engine speed NE at that time. For this reason, the diesel engine 2
First acceleration smoothing amount MQSMAD for each of various acceleration states
It is possible to adapt the optimum switching timing from 1 to the second acceleration smoothing amount MQSMAD2. (B) First half of acceleration (period before timing t1)
Then, the relatively large first acceleration smoothing amount MQSMAD1
Is used to obtain the acceleration smoothing injection amount QSMA, and in the latter half of the acceleration (the period after the timing t1), the acceleration is not performed using the second acceleration smoothing amount MQSMAD2 smaller than the first acceleration smoothing amount MQSMAD1. Furthermore, the injection amount QSMA is required. Therefore, in the first half of acceleration, the fuel injection amount can be increased with emphasis on power performance, and in the latter half, the fuel injection amount can be increased with emphasis on reduction of smoke. In other words, if the acceleration smoothing injection amount QSMA is to be obtained by one acceleration smoothing amount, either power performance or smoke reduction will be prioritized and the rest will be sacrificed. Can be compatible.

(C) In accelerating the diesel engine 2, two types of acceleration smoothing amounts MQSMAD1 and MQSMA
Only by increasing the basic injection amount QBASE using D2, both power performance and smoke reduction are achieved. Therefore, the maximum injection amount QFUL used in the conventional technique
A transient intake pressure correction coefficient MQFPT for reducing L,
Also, it is not necessary to gradually change the fuel injection amount after the reduction (the average injection amount). Along with this, these transient intake pressure correction coefficient M for achieving both power performance and smoke reduction
There is no need for a complex adaptation of the QFPT and the average injection quantity.
Two kinds of acceleration smoothing amount MQSMAD1, MQSMAD2
And the injection amount QNMS alone can be adapted for both power performance and smoke reduction, and can be easily adapted.

The present invention can be embodied in another embodiment shown below. (1) The present invention can also be applied to the case where the acceleration smoothing is not performed when the deviation ΔQ between the maximum injection amount QFULL and the pre-cylinder correction final injection amount QFINA is larger than the injection amount QNMS.

(2) In the above embodiment, the acceleration smoothing amount M is determined by the magnitude relationship between the deviation ΔQ and one injection amount QNMS.
Although the QSMAD1 and the MQSMAD2 are switched, a plurality of injection amounts QNMS may be prepared and the acceleration smoothing amount may be changed in multiple stages depending on the magnitude relationship between them and the deviation ΔQ.

Although the respective embodiments of the present invention have been described above, technical ideas other than the claims which can be understood from the respective embodiments will be described below together with their effects. (A) In the control device according to claim 1, when the acceleration state of the diesel engine is detected by the acceleration detection means, the basic injection amount correction means has a predetermined difference between the maximum injection amount and the basic injection amount. Diesel that increases the basic injection amount at a predetermined increase rate in a larger region, and increases the basic injection amount at a smaller increase rate than the predetermined increase rate in a region where the deviation is smaller than a predetermined value. Engine control unit. With such a configuration, power performance can be prioritized in the former region, smoke reduction can be prioritized in the latter region, and both requirements can be met.

[0069]

As described above in detail, according to the present invention, in the diesel engine in which the exhaust gas recirculation mechanism stops the exhaust gas recirculation at the time of acceleration, the basic injection amount changes with time during the acceleration of the engine. The rate of increase is set to be smaller as the basic injection amount approaches the maximum injection amount. Therefore, during acceleration of the diesel engine, it is possible to prevent a sudden change in the output torque while suppressing the occurrence of smoke due to a response delay when the exhaust gas recirculation mechanism is stopped.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention.

FIG. 2 is a schematic configuration diagram of a diesel engine and a fuel injection pump.

FIG. 3 is a block diagram showing an electrical configuration of an ECU.

FIG. 4 is a flowchart illustrating a fuel injection control routine.

FIG. 5 is a flowchart for explaining a fuel injection control routine of the same.

FIG. 6 is a flowchart illustrating an EGR control routine.

FIG. 7 is a timing chart showing changes in each injection amount.

FIG. 8 is a timing chart showing changes in each injection amount in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump, 2 ... Diesel engine (diesel engine), 35 ... Revolution speed sensor which comprises a part of operating state detection means, 54 ... Recirculation pipe which comprises a part of exhaust gas recirculation mechanism, 55 ... Exhaust gas EGR valve that constitutes a part of the gas recirculation mechanism, 56 ... VSV that constitutes a part of the exhaust gas recirculation mechanism, 73 ... Accelerator opening sensor that constitutes a part of operating state detection means, 74 ... Operating state detection Intake pressure sensor constituting a part of the means, 81 ... Basic injection amount calculation means,
CPU constituting the maximum injection amount calculation means, exhaust gas recirculation control means, basic injection amount correction means, final injection amount setting means, injection control means and acceleration detection means, NE ... Engine speed, VPIM ... Intake pressure, ACCP ... Accelerator opening, Q
FULL ... maximum injection amount, QBASE ... basic injection amount.

Claims (1)

[Claims] 1. A fuel injection pump for supplying fuel to a diesel engine, an exhaust gas recirculation mechanism for recirculating part of exhaust gas accompanying combustion of the fuel and intake air to the diesel engine, the diesel engine. An operating state detecting means for detecting an operating state of the engine, a basic injection amount calculating means for calculating a basic injection amount to the diesel engine according to the engine operating state by the operating state detecting means, and an engine operation by the operating state detecting means. A maximum injection amount calculation means for calculating a maximum value of an injection fuel amount combusted in intake air to the diesel engine based on a state; an acceleration detection means for detecting an acceleration state of the diesel engine; and the acceleration detection means. When accelerating the diesel engine by
Exhaust gas recirculation control means for stopping recirculation of exhaust gas by the exhaust gas recirculation mechanism, and during acceleration of the diesel engine by the acceleration detection means,
A basic injection amount correction unit that increases the basic injection amount by the basic injection amount calculation unit with time, and decreases the rate of increase as the basic injection amount approaches the maximum injection amount by the maximum injection amount calculation unit; The basic injection amount by the injection amount correction unit is limited to the maximum injection amount by the maximum injection amount calculation unit, and the final injection amount setting unit that sets the final fuel injection amount; A control device for a diesel engine, comprising: an injection control unit that matches a fuel injection amount to the engine with a final injection amount set by the final injection amount setting unit.